''Roseaplagis artizona'' is a species of

sea snail Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...

in the family Trochidae, the top snails.

Description

The height of the shell attains 3.5 mm, its diameter 4 mm. The very small shell is subperforate or imperforate. It has a conical shape. It is slightly iridescent and shining. The sculpture consists of fine spiral lirae, about 15 on the penultimate whorl. The growth lines are inconspicuous. It has a light yellow colour with radiate oblique broad streaks of dark brown. The intervals are filled with a few light brown dots. The base of the shell is tessellated with yellowish and brown. The epidermis is very thin, the pearly inner layer shining partly through it. The spire is conic with its height greater than that of the aperture. The sides are very slightly convex. The

protoconch A protoconch (meaning first or earliest or original shell) is an embryonic or larval shell which occurs in some classes of molluscs, e.g., the initial chamber of an ammonite or the larval shell of a gastropod. In older texts it is also called ...

is small, acute, and consists of two convex, light-brown, and finely spirally striate

whorl A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs). Whorls in nature File:Photograph and axial plane floral ...

s. The six whorls are flatly convex. The

body whorl The body whorl is part of the morphology of the shell in those gastropod mollusks that possess a coiled shell. The term is also sometimes used in a similar way to describe the shell of a cephalopod mollusk. In gastropods In gastropods, the b ...

is keeled at the periphery. The base of the shell is convex. The sutures are very little impressed. The slightly oblique aperture is subquadrangular. The interior is silvery and finely lirate. The outer and basal lip are sharp, angled where they meet, margined with a white bead. The columella is subvertical, slightly arched, with a slight swelling in the middle. The umbilicus is partly or completely covered by the columella expansion. The white umbilical tract is slightly impressed. Suter H. (1913-1915), Manual of New Zealand Mollusca; Wellington, N. Z. :J. Mackay, govt. printer,1913-1915
(described as ''Gibbula micans'')

Distribution

This marine species is endemic to New Zealand.

References

* Adams, A. 1853. ''Contributions towards a monograph of the Trochidae, a family of gasteropodous Mollusca''. Proceedings of the Zoological Society of London 19 1851: 150-192. * Powell, A.W.B. 1979: ''New Zealand Mollusca: Marine, Land and Freshwater Shells''. Collins, Auckland 500p * Marshall B.A. 1998. ''The New Zealand Recent species of Cantharidus Montfort, 1810 and Micrelenchus Finlay, 1926 (Mollusca: Gastropoda: Trochidae).'' Molluscan Research 19(1): 107-156 {{Taxonbar, from1=Q28950211, from2=Q7990178 artizona Gastropods of New Zealand Gastropods described in 1853